Liu et al. (2025) Characterizing Shallow Cumulus and Its Drivers Over the Tibetan Plateau

⚠️ Warning: This summary was generated from the abstract only, as the full text was not available.

Identification

• Journal: Journal of Geophysical Research Atmospheres
• Year: 2025
• Date: 2025-11-29
• Authors: Jiarui Liu, Kun Yang, Jiamin Wang, Hui Lü, Deliang Chen
• DOI: 10.1029/2025jd044893

Research Groups

Based on the abstract, specific research groups or departments are not explicitly mentioned.

Short Summary

This study investigates the macrophysical characteristics and environmental controls of shallow cumulus (ShCu) over the Tibetan Plateau (TP) using 15 years of satellite observations and reanalysis data. It reveals a distinct ShCu regime primarily controlled by near-surface relative humidity, with lower cloud bases compared to surrounding regions, offering insights for improved cloud parameterization.

Objective

• To analyze the macrophysical characteristics and environmental controls of shallow cumulus (ShCu), defined as cumulus with depth ≤ 2 km, over the Tibetan Plateau (TP).

Study Configuration

• Spatial Scale: Tibetan Plateau (TP) and surrounding regions.
• Temporal Scale: 15 years (2006–2020).

Methodology and Data

• Models used: ERA5 reanalysis (used as a data source for environmental drivers).
• Data sources: CloudSat satellite observations, CALIPSO satellite observations, ERA5 reanalysis, high-resolution topography data.

Main Results

• Shallow cumulus (ShCu) is defined as cumulus with a depth of less than or equal to 2 kilometers.
• ShCu occurs most frequently in summer and during the daytime, with the highest cloud fractions observed over the western and southeastern TP.
• ShCu dominates cumulus across all seasons, accounting for approximately 75% of the annual cumulus over the TP.
• Near-surface relative humidity (RH2m) is identified as the primary environmental control, regulating both ShCu occurrence and dominance.
• Moderate RH2m levels favor frequent and dominant ShCu by promoting condensation while limiting deep convection, particularly in the western TP year-round.
• In contrast, highly moist conditions combined with strong updrafts at 500 hPa in the southeastern TP during summer promote cloud deepening, resulting in lower ShCu cloud fraction (approximately 8.8%) and dominance (approximately 0.62) compared to the western TP (approximately 14.4% cloud fraction, approximately 0.80 dominance).
• ShCu over the TP exhibits a lower average cloud base (approximately 0.83 kilometers) than in surrounding regions.
• The lowest cloud base values are observed over the western TP during winter and nighttime, which are closely linked to reduced lifting condensation levels.

Contributions

• Highlights a distinct shallow cumulus (ShCu) regime specific to the Tibetan Plateau.
• Offers valuable insights for improving the parameterization of ShCu in atmospheric models by emphasizing the importance of incorporating terrain complexity and realistic near-surface humidity.

Funding

Funding information is not provided in the abstract.

Citation

@article{Liu2025Characterizing,
  author = {Liu, Jiarui and Yang, Kun and Wang, Jiamin and Lü, Hui and Chen, Deliang},
  title = {Characterizing Shallow Cumulus and Its Drivers Over the Tibetan Plateau},
  journal = {Journal of Geophysical Research Atmospheres},
  year = {2025},
  doi = {10.1029/2025jd044893},
  url = {https://doi.org/10.1029/2025jd044893}
}